By Julie Alvira, M.D., North Dallas LIVING WELL Magazine
The hype of soy is everywhere––from weight loss to protein powders to Asian restaurants where everybody is eating the delicious Edamame. It is a food good for women (in most cases), but what about men? Are men aware of the dilemma of the relationship of soy and testosterone levels? As I said, it is a dilemma. But let’s start with the basics.
The basics of soy
Soy is a name usually used for anything derived from the soybean, which is a natural grain from Asia. It can be processed into soy-based foods and beverage products. Textured soy protein (50-70% soy protein) is a meat substitute, while soy protein isolate (90% soy protein) is used for cereals, granola bars, sports drinks, dairy, etc. Soy is a popular food additive because it has no cholesterol, unsaturated fats, it is high in fiber, and lactose-free. According to The University of Maryland Medical Center (2013), people from Asia eat soy foods due to its association with reducing menopausal symptoms and lowering the risk of heart disease and osteoporosis. Soy has phytoestrogens (100 or more) which are naturally plant compounds that are structurally similar to mammalian estrogens. The most known researched group in phytoestrogens is the isoflavones which are present in berries, wine, grains, and nuts but most abundant in soybeans. Daidzein and genistein are the most well known isoflavones that are consumed by humans mostly through soy- based foods (Patisal & Jefferson, 2010). There is ongoing research of how phytoestrogens can reduce or increase the effects of estrogen in the body of men and women as well as its use in cancer.
Medical uses
A majority of studies suggest that ingesting soy foods can help with conditions such as: high cholesterol, high blood pressure, type 2 diabetes, asthma, lung, endometrial, prostate, breast, and thryroid cancer, osteoporosis, and can slow the progression of kidney disease. According to the Physicians Committee for Responsible Medicine (2013) soy also helps with constipation, diarrhea, decrease protein in urine of people with kidney disease, improves memory, breast pain, menopausal symptoms, and premenstrual symptoms.
The Food and Drug Administration and The American Heart Association (AHA) recommend 25 grams of soy protein as part of a diet that is low in cholesterol and saturated fat.
Cancer and Osteoporosis in women
Studies have shown that women that ingest daily soymilk or tofu have about 30 percent less risk of developing hormone related cancers such as breast cancer. In women that already suffer from the disease, soy can have a positive effect as well. Evidence suggests that soy can cut the recurrence or mortality in half (ShuXo, Zheng Y, Cai H, et al., 2009) because isoflavones block the effects of estrogens. Soy also prevents osteoporosis by increasing bone mineral density (BMD). In these cases, the isoflavones are responsible to increase the BMD in women with high soy ingestion in their diets.
Men and Soy
It is already known that testosterone is a hormone predominant in men. Testosterone plays a main character role in muscular development, libido, and bone development. Men also have small amounts of estrogen. As they age, testosterone levels tend to decrease with lean muscle mass. When this happens, it is said that estrogen levels tend to increase as well as an increase in body fat. Many studies claim that the isoflavones in soy can increase estrogen levels in men. One study found that men who consumed soy protein powder experienced a decrease in testosterone levels, while another study concluded lower sperms counts in the male participants. All levels increased after soy products were discontinued. The Harvard School of Public Health in Boston also made a study that appeared in the Journal of Human Reproduction suggesting that men who consume high amounts of soy foods can have low sperm count as well as low testosterone levels (Teller, 2012). The relationship with gynecomastia, erectile dysfunction, and other related conditions in men is still under study. What is suggested is that men 40 and above limit soy intake until more studies are revealed. Look at the ingredients in products and practice moderation.
Julie Alvira, M.D,. holds a MBA in healthcare management, and is the owner of AJBodysculpt and a personal fitness and nutrition coach. You can email her at ajbodysculpt@gmail.com. YouTube: www.youtube.com/user/2013bodysculpt.
References
Patisal, H., & Jefferson, W. (2010). The pros and cons of phytoestrogens. Font Neuroendocrinol, 31(4), 400-419. doi: 10.1016/j.yfme.2010.03.003
Physicians Committee for Responsible Medicine. (2013). Soy and your health. Retrieved from http://www.pcrm.org
Shu, Xo., Zheng, Y., Cai, H., Gu, K., Chen, Z., Zheng, W., & Lu, W. (2009). Soy food intake and breast cancer survival. Journal of the American Medical Association, 302(22), 2437-2443.
Teller, R. (2012). Soy lowers men’s testosterone levels and increases estrogen. Retrieved from http://www.1vigor.com
University of Maryland Medical Center. (2012). Retrieved from http://umm.edu
